Recently, there has been increasing interest in energy storage technology. As batteries have been widely used as energy sources in portable phones, camcorders, notebook computers, PCs and electric cars, research and development of electrochemical devices have been made intensively. In this regard, electrochemical devices are subjects of great interest. Particularly, development of rechargeable secondary batteries has been the focus of attention. More recently, research and development of an electrode and a battery having a novel design have been conducted in order to improve capacity density and specific energy thereof.
Among the currently used secondary batteries, lithium secondary batteries, developed in early 1990's, have drive voltage and energy density higher than those of conventional batteries using aqueous electrolytes (such as Ni-MH batteries, Ni—Cd batteries and H2SO4—Pb batteries), and thus are spotlighted in the field of secondary batteries. However, a lithium secondary battery has a problem in that it undergoes degradation of quality during repeated charge/discharge cycles. Such problems become more serious as the capacity density of the battery increases.
Therefore, there is a continuous need to develop a means for improving lifespan of a secondary battery.
Japanese Laid-Open Patent No. 2002-158034 discloses an acrylic compound as an additive for an electrolyte, the acrylic compound being able to inhibit gas generation in a lithium secondary battery and deterioration of an anode. Additionally, Japanese Laid-Open Patent No. 2003-168479 discloses that the use of an acrylic compound having at least three acryl groups as an additive for an electrolyte in a lithium secondary battery leads to formation of a solid electrolyte interface (SEI) layer via reduction at an anode, and such SEI layers inhibit decomposition of the electrolyte at the anode so as to improve lifespan characteristics of the battery.